The biggest problem is that they are using historical returns, that means that they are using.

• 1.8% for one year
• 20.4% for 3 years.

But you aren't modeling a 180,000 investment for three years. You have a 5,000 investment for 36 months another 5,000 for 35 months...

You have to know the interest rates for each of the 36 months.

The biggest problem is that they are using historical returns, that means that they are using.

• 1.8% for one year
• 20.4% for 3 years.

But you aren't modeling a 180,000 investment for three years. You have a 5,000 investment for 36 months another 5,000 for 35 months...

You have to know the interest rates for each of the 36 months....but you don't know them